# Increment and Display Digits in Assembly

This example demonstrates a simple assembly program that displays and increments the digits '1' through '10' on the screen. The program uses Linux system calls to perform these operations.

```assembly
section	.text
    global _start    ; Entry point for the program
	
_start:             ; Start of the program
    mov ecx, 10     ; Initialize loop counter to 10
    mov eax, '1'    ; Load ASCII value of '1' into EAX
	
l1:                 ; Start of loop l1
    mov [num], eax  ; Store the ASCII value in memory location 'num'
    mov eax, 4      ; System call number (sys_write)
    mov ebx, 1      ; File descriptor (stdout)
    push ecx        ; Save loop counter
	
    mov ecx, num    ; Load address of 'num' into ECX
    mov edx, 1      ; Set length to 1 (single character)
    int 0x80        ; Call kernel to display the character
	
    mov eax, [num]  ; Load ASCII value from memory into EAX
    sub eax, '0'    ; Convert ASCII to decimal
    inc eax         ; Increment the decimal value
    add eax, '0'    ; Convert back to ASCII
    pop ecx         ; Restore loop counter
    loop l1         ; Repeat the loop if counter is not zero
	
    mov eax, 1      ; System call number (sys_exit)
    int 0x80        ; Call kernel to exit program

section .bss
num resb 1          ; Storage for the ASCII value
```

### Code Explanation:

The provided assembly code achieves its goal through the following steps:

1. **Setting Up the Loop:**
   * The program starts by initializing a loop counter `ecx` with the value 10.
   * The ASCII value of '1' is loaded into the `eax` register, which will be used to display the digits.
2. **Loop Execution:**
   * The program enters a loop labeled `l1`, where each iteration performs the following actions:
     * Stores the ASCII value in the memory location `num`.
     * Uses the `sys_write` system call to display the character stored in the `num` memory location.
     * Converts the ASCII value in `num` to decimal, increments it, and converts it back to ASCII.
     * Preserves the loop counter using the `push` instruction to maintain its value between iterations.
     * Repeats the loop using the `loop` instruction as long as the loop counter is not zero.
3. **Program Termination:**
   * After the loop completes, the program uses the `sys_exit` system call to terminate.

### Example:

Consider the following example of running the program:

```assembly
section	.text
    global _start

_start:
    mov ecx, 10      ; Initialize loop counter to 10
    mov eax, '1'     ; Load ASCII value of '1' into EAX

l1:
    mov [num], eax   ; Store ASCII value in memory location 'num'
    mov eax, 4       ; System call number (sys_write)
    mov ebx, 1       ; File descriptor (stdout)
    push ecx         ; Save loop counter

    mov ecx, num     ; Load address of 'num' into ECX
    mov edx, 1       ; Set length to 1 (single character)
    int 0x80         ; Call kernel to display the character

    mov eax, [num]   ; Load ASCII value from memory into EAX
    sub eax, '0'     ; Convert ASCII to decimal
    inc eax          ; Increment the decimal value
    add eax, '0'     ; Convert back to ASCII
    pop ecx          ; Restore loop counter
    loop l1          ; Repeat loop if counter is not zero

    mov eax, 1       ; System call number (sys_exit)
    int 0x80         ; Call kernel to exit program

section .bss
num resb 1           ; Storage for the ASCII value
```

When you assemble and run this program, it will display the digits '1' through '10' on the screen.

***


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://talaatmagdyx.gitbook.io/assembly-code-snippet/increment-and-display-digits.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.